ssl: fix NPN support

As of commit 4eb4b32 ("Remove support for OpenSSL 0.9.8 and 1.0.0",
2016-11-30), ext/openssl/extconf.rb don't check for existence of
SSL_CTX_set_next_proto_select_cb() function, but the code still refers
to the HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB macro. NPN is available in
all supported versions of OpenSSL and LibreSSL, unless it's disabled by
their configure options. Check OPENSSL_NO_NEXTPROTONEG macro instead.

Author: rhenium

ext/openssl/ossl_ssl.c

@@ -582,7 +582,7 @@ ssl_renegotiation_cb(const SSL *ssl)
     (void) rb_funcall(cb, rb_intern("call"), 1, ssl_obj);
 }
 
-#if defined(HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB) || \
+#if !defined(OPENSSL_NO_NEXTPROTONEG) || \
     defined(HAVE_SSL_CTX_SET_ALPN_SELECT_CB)
 static VALUE
 ssl_npn_encode_protocol_i(VALUE cur, VALUE encoded)
@@ -667,7 +667,7 @@ ssl_npn_select_cb_common(SSL *ssl, VALUE cb, const unsigned char **out,
 }
 #endif
 
-#ifdef HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB
+#ifndef OPENSSL_NO_NEXTPROTONEG
 static int
 ssl_npn_advertise_cb(SSL *ssl, const unsigned char **out, unsigned int *outlen,
 		     void *arg)
@@ -881,7 +881,7 @@ ossl_sslctx_setup(VALUE self)
     val = rb_attr_get(self, id_i_verify_depth);
     if(!NIL_P(val)) SSL_CTX_set_verify_depth(ctx, NUM2INT(val));
 
-#ifdef HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB
+#ifndef OPENSSL_NO_NEXTPROTONEG
     val = rb_attr_get(self, id_i_npn_protocols);
     if (!NIL_P(val)) {
 	VALUE encoded = ssl_encode_npn_protocols(val);
@@ -2164,7 +2164,7 @@ ossl_ssl_get_client_ca_list(VALUE self)
     return ossl_x509name_sk2ary(ca);
 }
 
-# ifdef HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB
+# ifndef OPENSSL_NO_NEXTPROTONEG
 /*
  * call-seq:
  *    ssl.npn_protocol => String | nil
@@ -2473,7 +2473,7 @@ Init_ossl_ssl(void)
      *   end
      */
     rb_attr(cSSLContext, rb_intern("renegotiation_cb"), 1, 1, Qfalse);
-#ifdef HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB
+#ifndef OPENSSL_NO_NEXTPROTONEG
     /*
      * An Enumerable of Strings. Each String represents a protocol to be
      * advertised as the list of supported protocols for Next Protocol
@@ -2656,7 +2656,7 @@ Init_ossl_ssl(void)
 # ifdef HAVE_SSL_CTX_SET_ALPN_SELECT_CB
     rb_define_method(cSSLSocket, "alpn_protocol", ossl_ssl_alpn_protocol, 0);
 # endif
-# ifdef HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB
+# ifndef OPENSSL_NO_NEXTPROTONEG
     rb_define_method(cSSLSocket, "npn_protocol", ossl_ssl_npn_protocol, 0);
 # endif
 #endif